Metro App Prevent BackgroundTask from Running if UI is Open

Question

I have a BackgroundTask which connects to a remote server and does some kind of action, download, upload, etc. This task runs every 15 minutes.

The UI associated to the BackgroundTask does the same and more.

However, the remote server allows only one session per login and I have only one login to that server. As such, I need a strategy to ensure that either one of these two are active and not both.

Currently, I store a value in LocalSettings which indicates if the UI is open or not. If the UI is closed, the BackgroundTask will do it's job as per normal. If the UI is open, the BackgroundTask will do nothing.

This works fine, except for when the BackgroundTask is in the middle of it's Run and the UI is launched. I need a way of cancelling this BackgroundTask immediately when the UI is launched, so that the UI can use the login to the remote server. Any tips or suggestions on how this may be achieved?

Answer 1

Thanks to Dave Smits for the solution.

In a nutshell:

• Register for Cancellation event in Run method.
• In the Cancellation event handler ensure connected sessions are disconnected.
• When the OnLaunched event is raised in the App object, Unregister the task which raises the task Cancellation event.